ghillert/spring-integration — comment on commit b12235d1e4a30b34a6f4e8a59a62cbb8c3416a05
File: src/reference/docbook/endpoint.xml line 530
By garyrussell:

Should emphasize the comment in the sample ReadMe here...

Because the Trigger method is nextExecutionTime(), any changes to a dynamic trigger will not take effect until the next poll based on the existing configuration. It is not possible to force a trigger to fire before it's currently configured next execution time.